1. Field of the Invention
The present invention relates to an article storage facility comprising an article storage rack having storage units arranged in a vertical direction and in a lateral direction, and an article transport device which is capable of transporting articles to each of the storage units in the article storage rack.
2. Description of the Related Art
An article storage facility such as one described above is used, for example, in an article transport facility, which includes an overhead transport device movable along a travel path provided near a ceiling and passing by a plurality of stations, to temporarily store articles to be transported by an overhead transport device to the stations. An article is, for example, a container for storing a plurality of semiconductor substrates. Each station is positioned on the floor in correspondence with each of a plurality of article processors which perform predetermined processing on semiconductor substrates. The overhead transport device is configured to transfer articles between stations by raising and lowering a grip portion which can grip an article with the article suspended from the grip portion.
And, in the article storage facility, the storage unit located in the upper most part of the article storage rack is configured to be a storage unit for taking articles in and out, into and out of which the overhead transport device can transfer an article, and the article transport device transports the articles between the storage unit for taking articles in and out and other storage units.
And, in a conventional article storage facility, a plurality of storage units in the article storage rack are arranged to form rows in the vertical direction and the lateral direction in the same position with respect to the fore and aft direction of the rack. The article transport device consists of a movable body which can move in the rack lateral width direction of the article storage rack, a vertically movable body which is guided and supported for vertical movement by a vertical movement guiding mast arranged vertically on the movable body, and an article support provided to the vertically movable body. And the article support is supported to the vertically movable body such that the article support can move, in the fore and aft direction of the article storage rack, between a projected position for article transfer with respect to the storage unit and a pulled back position away from the storage unit. (See, for example, Patent Document 1.)
In this conventional article storage facility, when the article transport device transfers an article to a storage unit, to which an article is to be transferred, among a plurality of storage units, after moving the article support to the position opposite the storage unit, which is the transfer target, by moving the movable body in the rack lateral width direction, and by raising and lowering the vertically movable body along the vertical movement guiding mast, the article to be transferred is transferred by moving the article support to project from the pulled back position to the projected position in the rack fore and aft direction.    Patent Document 1: Japanese Patent Application Publication No. H9-315521